THE NEW YORK TIMES reports that Walt Disney's pending acquisition of Marvel Ent. has hit a legal issue regarding the rights of some of its major characters. Last week, the heirs of comic book artist Jack Kirby, a creator on such characters as X-MEN and FANTASTIC FOUR, sent 45 copyright termination notices to Marvel, Disney, Paramount Pictures, Sony Pictures, 20th Century Fox, Universal Pictures, and other companies that have licenses to characters Kirby created.

Toberoff & Associates, the firm behind the SUPERMAN rights lawsuit that successful returned a portion of the copyright to Jerome Siegel's heirs, is representing Kirby's heirs. The notices want some rights to revert back to the heirs as soon as 2014.

Disney said in a statement, “the notices involved are an attempt to terminate rights 7 to 10 years from now, and involve claims that were fully considered in the acquisition.”

If the Kirby heirs win, in addition to gaining a share of profits on projects based on Kirby-created superheroes, the heirs would have the right to sell the rights to the characters without Marvel's consent.